scholarly journals Drug sensitivity and mutability to drug resistance associated with the presence of an R factor

1971 ◽  
Vol 17 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Masanosuke Yoshikawa
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Drug Resistance ◽  
Growth Kinetics ◽  
Rapid Growth ◽  
Drug Sensitivity ◽  
Host Bacterium ◽  
R Factor ◽  
Rapid Growth Rate ◽  
Kinetics Of

SUMMARYStudies on the growth kinetics of R+and R−cultures ofEscherichia coliin the presence of nalidixic acid (NA), acriflavine (AF) and kanamycin (Kan) showed that each drug caused a decline in viability of both R+and R−cells for several hours. During further incubation the viability rose rapidly for the R+cultures, but either rose less rapidly (AF and Kan) or continued to decline (NA) for R−cultures. Distribution curves of the resistances of individual clones of R+and R−bacteria to atabrine, NA, AF and Kan suggested that the presence of an R factor in the host bacterium increased its mutation rate to resistance to these drugs: this would account for the more rapid growth rate of R+cells during the latter stages of incubation in their presence. The mutations causing increased resistance to NA and to Kan were located in the bacterial chromosome and not in theRfactor.

Growth kinetics of Escherichia coli with galactose and several other sugars in carbon-limited chemostat culture

1999 ◽  
Vol 46 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Urs Lendenmann ◽  
Mario Snozzi ◽  
Thomas Egli
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Steady State ◽  
Specific Growth Rate ◽  
Growth Kinetics ◽  
Specific Growth ◽  
Chemostat Culture ◽  
Monod Model ◽  
E Coli ◽  
Kinetics Of

Kinetic models for microbial growth describe the specific growth rate (μ) as a function of the concentration of the growth-limiting nutrient (s) and a set of parameters. A typical example is the model proposed by Monod, where μ is related to s using substrate affinity (Ks) and the maximum specific growth rate (μmax). The preferred method to determine such parameters is to grow microorganisms in continuous culture and to measure the concentration of the growth-limiting substrate as a function of the dilution rate. However, owing to the lack of analytical methods to quantify sugars in the microgram per litre range, it has not been possible to investigate the growth kinetics of Escherichia coli in chemostat culture. Using an HPLC method able to determine steady-state concentrations of reducing sugars, we previously have shown that the Monod model adequately describes glucose-limited growth of E. coli ML30. This has not been confirmed for any other sugar. Therefore, we carried out a similar study with galactose and found steady-state concentrations between 18 and 840 μg·L-1 for dilution rates between 0.2 and 0.8·h-1, respectively. With these data the parameters of several models giving the specific growth rate as a function of the substrate concentration were estimated by nonlinear parameter estimation, and subsequently, the models were evaluated statistically. From all equations tested, the Monod model described the data best. The parameters for galactose utilisation were μmax = 0.75·h-1 and Ks = 67 μg·L-1. The results indicated that accurate Ks values can be estimated from a limited set of steady-state data when employing μmax measured during balanced growth in batch culture. This simplified procedure was applied for maltose, ribose, and fructose. For growth of E. coli with these sugars, μmax and Ks were for maltose 0.87·h-1, 100 μg·L-1; for ribose 0.57·h-1, 132 μg·L-1, and for fructose 0.70·h-1, 125 μg·L-1. Key words: monod model, continuous culture, galactose, glucose, fructose, maltose, ribose.

scholarly journals An assessment of Brazilian conservation units – a second look

2012 ◽  
Vol 15 (1) ◽  
Author(s):  
José Augusto Leitão Drummond ◽  
José Luiz De Andrade Franco ◽  
Daniela De Oliveira
Keyword(s):  
Growth Rate ◽  
Protected Areas ◽  
National Parks ◽  
Rapid Growth ◽  
Sustainable Use ◽  
Conservation Unit ◽  
Conservation Units ◽  
Unit System ◽  
Rapid Growth Rate ◽  
Fourth Position

This is a second overview of the Brazilian conservation unit system for mid-2010. It updates author et al, 2009. It examines six dimensions of federal and state protected areas – age, numbers, types of units, absolute and average sizes, distribution by states and biomes, and degree of compliance with CBD-inspired goals. Major findings: (i) the system maintained a rapid growth rate; (ii) national parks and national forests are the most prominent units; (iii) distribution of units by region and biome remains unbalanced; (iv) state units grew remarkably over the last five years; (v) state units are biased towards sustainable use; (vi) sustainable use units grew more than fully protected units; (vii) Amazonia remains the most extensively protected biome; and (viii) quantitative goals of biome protection are closer to being reached. In 2010 Brazil held the fourth position globally in protected areas; it created the largest number of units between 2000 and 2010; it has the largest combined area of protected tropical formations. However, several regions and biomes remain under protected. 

scholarly journals Characterization of the β-lactamase specified by the resistance factor R-1818 in Escherichia coli K12 and other Gram-negative bacteria

1971 ◽  
Vol 123 (4) ◽  
pp. 501-505 ◽  
Author(s):  
J. W. Dale
Keyword(s):  
Escherichia Coli ◽  
Host Species ◽  
Host Bacterium ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
R Factor ◽  
Relationship Of ◽  
The Relationship

1. The amino acid composition of the β-lactamase from E. coli (R-1818) was determined. 2. The R-1818 β-lactamase is inhibited by formaldehyde, hydroxylamine, sodium azide, iodoacetamide, iodine and sodium chloride. 3. The Km values for benzylpenicillin, ampicillin and oxacillin have been determined by using the R-factor enzyme from different host species. The same values were obtained, irrespective of the host bacterium. 4. The molecular weight of the enzyme was found to be 44600, and was the same for all host species. 5. The relationship of R-1818 and R-GN238 β-lactamases is discussed.

Growth Kinetics and Formation of Uniform Self-Assembled InAs/GaAs Quantum Dots at

2007 ◽  
Vol 124-126 ◽  
pp. 539-542
Author(s):  
Eui Tae Kim ◽  
Anupam Madhukar
Keyword(s):  
Growth Rate ◽  
Quantum Dots ◽  
Growth Kinetics ◽  
Slow Growth ◽  
Fast Growth ◽  
Slow Growth Rate ◽  
Self Assembled ◽  
Kinetics Of ◽  
Fast Growth Rate ◽  
2D To 3D

We discuss the growth kinetics of InAs/GaAs self-assembled quantum dots (QDs) using two different InAs deposition rates, relatively fast growth rate of 0.22 ML/sec and slow growth rate of 0.054 ML/sec. With increasing InAs deposition amount to 3.0 ML, the QD density was almost constant after 2D to 3D island transition at the slow deposition rate while the QD density kept increasing and the QD size distribution was relatively broad at the fast growth rate. After the 2D to 3D transition, at the slow growth rate, further deposited In adatoms seemed to incorporate primarily into already formed islands, and thus contribute to equalize island size. The photoluminescence (PL) full-width at half maximum (FWHM) of 2.5 ML InAs QDs at 0.054 ML/sec was 23 meV at 78K. The PL characteristics of InAs/GaAs QDs were degraded significantly after thermal annealing at 550 oC for 3 hours.

scholarly journals Meagre (Argyrosomus regius Asso, 1801) aquaculture in Croatia

2016 ◽  
Vol 74 (1) ◽  
pp. 14-19 ◽  
Author(s):  
Nikolina Kružić ◽  
Bosiljka Mustać ◽  
Ivan Župan ◽  
Slavica Čolak
Keyword(s):  
Growth Rate ◽  
Rapid Growth ◽  
Adriatic Sea ◽  
Current Status ◽  
Migratory Fish ◽  
Important Species ◽  
Argyrosomus Regius ◽  
Rapid Growth Rate ◽  
Interesting Candidate ◽  
Year 2000

Abstract The objective of this review is to present current status of meagre aquaculture in Croatia. Meagre Argyrosomus regius (Asso, 1801) is a fast growing migratory fish species which used to be widespread along the coast of the Adriatic Sea. Today, it is very rare in fisheries catches and is considered highly endangered. Recently, meagre has become an increasingly important species in the Mediterranean aquaculture. In Croatia, meagre is a relatively new cultured species whose farming started after the year 2000. Since the European Commission identified species diversification as a top priority in the framework of the 2020 strategies for Aquaculture, and with recent studies revealing that meagre adapt easily to captivity and maintain a rapid growth rate, this species became an interesting candidate for Croatian as well as Mediterranean aquaculture.

Sign in / Sign up

Export Citation Format

Share Document